High-frequency shorting block



April 26, 1949.

P. A. VONADA HIGH-FREQUENCY SHORTING BLOCK Filed Sept. 6, 1944IIIIIIIIIIJIIIIJIIII.

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/ P6711606? war/90 9 BY B. 644/ Patented Apr. 26, 1949 UNITED STA'EELSPATENT OFFICE (Granted under the. act at" Mairch- 3; 1883, as amendedAiprili 30; 1928;. 3 70 G. 757.)

k @laiim The invention described; herein may be manufactured and used byor' for the Government: for governmental" purposes, without the paymentto me of any royalty thereon.

The invention to be hereinafter described relates to coaxial tuningstubs.

In the radio field tuning devices are widely used and there are severalwell known types. One of the more. widely known. types uses adi'sc, heador plate of considerable. diameter reciprocable on a central or innerconductor and'carrying a plurality of peripheral leaf. spring contactsin sliding engagement with the outer conductor; The usualv screw feed isused to travel. the. disc in tuning the set. To adequately. guide thedisc, a pair of guide rods is used at. considerable distances from the.disc center and parallel with the direction of travel of the disc.Frequently there is. binding between the disc. and: guide rods,rendering the device wholly inoperative,. seriously inefiicient or,v atleast, greatly impairing the efficiency of the device. Anotherdifficulty in that type is the. tendency of the leaf. springs. to. missengagement or contact thereby changing capacity and. correspondinglyimproperly affecting frequency or tuning.

The main objects; of the present invention are to avoid the above andother objections and provide a simple, efficient and compact coaxialtuning stub which may be readily provided in quantity at low cost.

In order to more clearly disclose the construction, operation and. useof the invention, reference should be had to the accompanying drawings.forming part of the. present application.

Throughout the several figuresof the, drawings like. referencecharacters designate the same parts in. the different views.

In the drawings Fig. 1 is a side elevation;

Fig. 2 is a lateral cross section on line 2-2 of Fig. 1;

Fig. 3 is a lateral cross section on line 3-3 of Fig. 1;

Fig. 4 is an enlarged side elevation of the swinging frame of thepinion, in operative position;

Fig. 5 is a view similar to Fig. 4, in inoperative position;

Fig. 6 is a plan view of Fig. 4;

Fig. 7 is a cross section on line 1-1 of Fi 6;

Fig. 8 is a lateral cross section of Fig. 1 on line 8-8, enlarged; and

Fig. 9 is an enlarged longitudinal cross section through the pistonhead.

all

Referringto the drawings in detail, I" indicates the outer conductor ofthe coaxial line and 2 the inner or central conductor. The inner orcentral" conductor is supported concentrically or coaxially' within theouter conductor 4 in usual and well known manner; Slidably disposed onsaid central conductor is a tubular sleeve 3 carrying at its innerendthe piston head, block or' stub having substantially the same outsidediameter asfheinside diameter of cylinder I-. It has a. free sliding fitwithin the outer conductor, continuous and. a wiping contact throughoutits cylindrical wall or face: with the inner wall or face of cylinder I.Sleeve 3 is appreciably" longer than conductor 1. Sleeve 3 is providedwith a radially extending rack 9 running the greater part of its lengthand meshing with a pinion 5 journaled in. a frame. 6 which is pivotedto. the lower part of the front portion of a plate l which extendsoutwardly from i" in the direction of travel of sleeve 3 and" is spacedradially from conductor 2, sleeve 3 and rack 4'. By this. pivotalmounting of frame 6 pinion 5' may be readily swung upwardly or radiallyto disengage it from rack 4. Normally, the. pinion gravitates toengagement or operative driving contact. with the rack. Preferably, itis operable by a handle or knob 8' on one. end. which, of course, mayalso be used. for raising the pinion to disengaged or inoperativeposition.

Rack 9,, extending radially from sleeve. 3,, provides. a, key, spline.or feather which is used to guide the'rack in its reciprocati'ons. Back9 passes centrally through the closed end of l and end" plate HI carriedthereby, both. the closed and and. plate I'll, being provided withcooperating aligned notches or slots H for such free. sliding andguiding movement. of the rack.

piston. head or tuning stub, 4 is of. sufficient Width or axial extentto assure ample contact at all times and in all positions with thecooperating inner wall of the outer conductor I. This width, togetherwith the single central or axial guide and longitudinal feed, provide asimple, continuous, definite, sure and non-binding feed of the sleeve 3and head or stub 4. A single feed rack acting at the center of the stubor head acts equally or is balanced in its action, avoiding canting,twisting and binding.

By eliminating the spring contact fingers, the diameter of the piston 4may be greatly reduced. That, in turn, enables corresponding reductionin the diameter of the outer conductor l, with resulting reduction inoverall size of the entire device.

By having the entire outer cylindrical wall of stub 4 in smooth slidingcontinuous contact with the inner cylindrical surface or wall of theouter conductor there will be a definite established uniform contactrelationship that will not vary with repeated use. That, obviously, isnot the case Where the multiple radial spring contact stub is used. Withthe stub of this invention there is no variation in capacity as with themultiple radial spring contact stub.

Fig. 9 shows, somewhat exaggerated, for clearness, the elements carriedby the piston head to doubly assure proper electrical conducting contactbetween the piston head and the two coaxial conductors l and 2.Resilient split rings l2 seated, peripherally in the piston head, inexpanded state, project radially very slightly beyond the cylindricalWall of the head. When compressed they are in the same plane as thepiston head cylindrical wall. So, when the piston is in place within lthe spring rings will be compressed and in constantly yieldin contactwith I. This pro vides double assurance of continued good electricalcontact with I throughout the periphery of the piston head, at alltimes. continued good electrical contact between the piston head and 2throughout the periphery of 2 is provided by a very small diameter coilspring l3 seated in the channel or groove l 4 in the center of 4surrounding 2. is, preferably, about /1000 of an inch less than thediameter of the spring seated therein. Thus, the encirclement diameterof spring I3 is /1000 inch less than the outer diameter of 2 which itencircles so that spring l3 exerts a continuous pressure on 2, beingcompressed between 4 and 2, with assured continuous contact between 2and 4 at all times.

Split rings l2, as shown, are seated in narrow shallow channels formedin the edges of 4, The outer walls of these channels, of course, may becompressed against the fiat split rings to properlyv seat them, in wellknown manner..

In the present construction, the whole stub assembly may be easily andquickly removed and reinserted as a single simple unit without anydissassembling and with the minimum disconnection. It is only necessaryto lift the frame 6 and pinion by knob 8 from the position of Fig. 4 tothe position of Fig. 5, thereby raising pinion 5 Like assurance of a Thedepth of that groove 4 readily determined in ways well known to thoseskilled in the art and need not be detailed or elaborated on in thisapplication as that would unnecessarily encumber and enlarge the recordof the case with no resulting gain or advantage.

Likewise, the small number of parts, together with the simplicity ofeach, greatly reduces manufacturing assembling, handling and shippingcosts. It also greatly increases durability and efliciency of theconstruction.

It is thought that the construction, operation and use of the inventionwill be clear from the preceding detailed description.

Changes may be made in the construction, arrangement and disposition ofthe several parts of the invention within the scope of the appendedclaim without departing from the field of the invention and it is meantto include all such within this application wherein only one preferredform of the invention has been disclosed purely by way of illustrationand with no thought or intention of, in any degree, limiting theinvention thereby.

Having thus described my invention, what I claim and desire to protectby Letters Patent is:

A coaxial tuning device comprising coaxial inner and outer conductors, atubular stub surrounding said inner conductor and positioned within saidouter conductor and in sliding contact with the outer and innercylindrical surfaces respectively of said conductors, first and secondchannels in the outer and inner cylindrical surfaces respectively ofsaid stub, a split ring in said first channel and in sliding contactwith the inner surface of the outer conductor, a coiled spring in saidsecond channel and in sliding contact with the outer surface of saidinner conductor, a tubular sleeve secured to said stub and surroundingsaid inner conductor and movable longitudinally thereof, alongitudinally disposed rack extending outwardly from said sleeve, apinion engageable with said rack, means to rotate said pinion, and meansto sustain said pinion and said rotating means pivotally relative tosaid outer conductor so as to allow said pinion to be moved into and outof engagement with said rack. said pinion being maintained normally inoperable engagement with said rack.

PHILLIP A. VONADA.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 2,106,769 Southworth Feb. 1, 19382,109,843 Kassner Mar. 1, 1938 2,280,728 Streib Apr. 21, 1942 2,379,047Thomas June 26, 1945

